(10) Crown Held in Abeyance, pending issuance of exploratory
license of occupation (as of May11, 1990)

4.3- Kidd-Munro Assemblage

This assemblage consists of ultramafic, pyroxenitic, and basaltic komatiite,
tholeiitic picrite, magnesium-rich tholeiite, high-alumina basalt, iron-rich
tholeiite, icelandite (andesite), and thin units of high-silica rhyolite
(Basaltic Volcanism Study Project 1981, Chapter 1.2; see Section 7.1.2.2
for discussion or high-silica rhyolite). Variolitic, massive, and pillowed
basalt units also occur (e.g., Leahy and Ginn 1961a,b; Arndt and Nesbitt
1982). Associated with these metavolcanic sequences are layered, tholeiitic
(e.g., Munro Lake Complex, Centre Hill Complex, McCool Hill Complex; MacRae
1969) and ultramafic intrusions. Lithologies generally strike east to southeasterly
and dip steeply. In the eastern part of the assemblage, units face both
to the north and south, which is attributed, in part, to the presence of
several east-striking folds and several east- to southeast-striking shear
zones. Facing and dip direction of units in the western part of the belt
are poorly constrained.

The most comprehensive descriptions of mafic and ultramafic flows are
for those which crop out in Munro Township (Arndt and Nesbitt 1982), the
location of the classic ultramafic komatiites of Pyke Hill (Pyke et al.
1973). Based on geochemical criteria several types of basalts are recognized
(Arndt and Nesbitt 1982): Type 1: LREE-depleted, flat HREE, low abundances
of incompatible elements; Type 2: flat REE, enriched in incompatible elements;
Type 3: Theo's flow basalts, strongly enriched in incompatible elements,
slightly enriched LREE pattern, fractionated HREE; 4) Warden Township basalts,
having trace element characteristics similar in some respects to those
of "Type 2" basalts (enriched incompatible elements, inferred flat REE
patterns). " Type 1" basalts could have been derived from a depleted mantle
source (Arndt and Nesbitt 1982). All other magmas could have come from
a second source which had roughly chondritic trace element ratios (Arndt
and Nesbitt 1982). The extent to which these detailed petrochemical relationships,
described from Munro Township, can be applied through the Kidd-Munro assemblage
remains to be confirmed.

Rhyolites and high-silica 2715 Ma (Barrie 1990) rhyolites in the western
part of the assemblage, near the Kidd Creek Mine, have relatively flat
REE patterns ([La/Yb] = 1-4), pronounced negative Eu anomalies (Eu/Eu =
0.20 to 0.61), low Zr/Y (2 to 6), high abundances of high field strength
elements, and low abundances of Sc and Sr (Lesher et al, 1986). Felsic
metavolcanic rocks from Beatty Township, in the eastern part of the Kidd-Munro
assemblage, have an age of 2714 +/ - 2Ma (Corfu et al. 1989).
This dated rhyolite is chemically similar to rhyolites in the western part
of Munro Township, and provides the probable age for the komatiites in
Munro Township. Rocks and associated base metal mineralization in Munro
Township are discussed in more detail In Section 6.3.

4.3.1. Contact Relationships

The northern contact of this assemblage with the Duff-Coulson-Rand assemblage
is not exposed, but locally appears to be coincident with a shear zone
having a dextral horizontal slip component (see discussion above). The
Pipestone shear zone defines the contact with the Hoyle assemblage to the
south (e.g., Leahy and Ginn 1961a). No kinematic analysis of this shear
zone has been carried out. This western contact of the assemblage is quite
irregular and it is not known if this reflects a stratigraphic or structural
interleaving of lithologies. It is not known if this assemblage extends
to the west of the Mattagami River fault (Fig. 4).

MINERAL DEPOSITS

Fyon and A.H. Green 2

The deposit-scale characteristics of deposits of several types, that
are represented in the Timmins area, are described in the following sections.
These descriptions provide the visitor with an overview of the geological
characteristics of the geological settings and related deposit types. These
descriptions form the basis for depositional models. Accompanying each
descriptive component, a tour guide is included. For some mines, the guides
are very brief, and of a philosophical nature, because active mining prohibits
the definition of a firm tour far in advance.
5.1. Time and Space Relationships
In this section, the mineral deposits are considered within the framework
of the proposed regional geological setting (Section 4.) and the available
geochronological constraints. Relevant gold and base metal production data
for mines in the Timmins area are summarized in Tables 1 and 2.

In the southwestern part of the Abitibi greenstone belt, polymetallic,
massive, base-metal sulphide mineralization occurs in the Kidd-Munro and
Kamiskotia assemblages. At the western end of the Kidd-Munro assemblage,
the giant (Table 2), stratiform, polymetallic Kidd Creek deposit occurs
associated with a sequence of massive to autobrecciated flows and pyroclastic
felsic metavolcanic rock and effusive and intrusive mafic and ultramafic
igneous rocks (see Section 7.2.). In the eastern part of the Kidd-Munro
assemblage, copper-zinc mineralization at the Potter Mine is hosted by
hyaloclastite units, within a sequence of tholeiitic olivine basalts and
komatiites (Coad 1976; see Section 6.3.3.). Felsic metavolcanic rocks within
the Kidd-Munro assemblage have ages of 2714 +/-2 (Beatty Township, immediately
west of Munro Township; Corfu et al. 1989) and approximately 2717 Ma (Kidd
Creek rhyolite; Barrie and Davis 1990). These dates provide a constraint
on the probable age of the Kidd Creek and Potter Mine
polymetallic, massive sulphide mineralization in this assemblage.

Polymetallic, massive, sulphide mineralization also occurs within the
Kamiskotia meta-igneous assemblage, associated with felsic and mafic metavolcanic,
rock within the Kamiskotia metavolcanic complex (see Section 7.1.). Zircon
ages for the Kamiskotia gabbroic complex and the Kamiskotia rhyolite are
2707+/-2 Ma and 2705 +/-2 Ma, respectively (Barrie and Davis 1990). Hence,
the polymetallic massive sulphide deposits in the Kamiskotia area appear
to have formed approximately 10 Ma after those in the Kidd-Munro assemblage.

The most important association of nickel mineralization in the Timmins
area is the komatiite-hosted one, and the area represents one of the best
examples of this type outside of the type example at Kambalda in the Yilgarn
block of Western Australia.

The purpose of this chapter is to provide basic information on nickel
deposits of this association in the Timmins area, and on the komatiites
and other rocks with which they are closely spatially associated. It is
the intention to provide information of a nature that will be helpful in
the development and refinement of ore deposit models for these deposits.
Some specific descriptions of field trip stops are given but, as with other
sections of the guide, it is not possible to guarantee access to mines
at the time of writing this guide.

6.1. Geological Setting
The komatiite suite of rocks, from basalt, pyroxenitic basalt, peridotite
and dunite (Arndt and Nisbet 1982) are well represented in the southern
half of the Abitibi Belt, as shown on figure 1. These rocks are most readily
identified by the distinctive spinifex texture, which is relatively common
in the upper parts of the flows of basaltic to pyroxenitic to peridotitic
composition. In areas of poor outcrop, the full extent of komatiites is
difficult to determine, hence the map is only an indication of their minimum
extent.

Sufficient evidence from precise U-Pb dating shows that the komatiites
are not all of the same age (see Sections 4.3, 4.6., 4.11.). However, there
are insufficient data to confirm the probably different ages of the komatiites
hosting nickel deposits in the Alexo-Dundonald and Shaw-Bartlett Dome areas.

6.2 Nickel Deposits of the Timmins Area
Known deposits in the Abitibi belt are clustered around the Timmins, Ontario
and Malartic, Quebec areas (Fig. 1). The only known dunite-hosted deposit
of the Mt. Keith association is the Dumont in Quebec (Duke 1986). All other
known deposits are associated with peridotitic komatiites, variously interpreted
as flows and sills. These are most commonly known as the Kambalda type
of deposits. Of the nine nickel deposits in the Timmins area (Table 2)
eight are hosted by komatiites. The ninth, the Montcalm deposit is hosted
by a tholeiitic intrusion. It has been described in detail by Barrie and
Naldrett (1989). The deposits are listed, with estimates of their sizes
and grades, in Table 2.
6.3. Pyke Hill, Munro Township
The Komatiites exposed on Pyke Hill in the
centre of Munro Township, Ontario (Fig. Nl1, Nl2),
have become accepted as a type example of ultramafic flows. Many of these
flows are layered with spinifex-textured upper parts and olivine cumulate
lower parts (Pyke et al. 1973). There is a regular variation in the size
and orientation of skeletal olivine grains in the spinifex textured lava,
from fine, randomly-oriented tablets at the tops of the flows, to larger,
parallel plates lower down. The presenceof spinifex
texture has become recognized as a diagnostic feature of komatiite
flows (Nesbitt 1971; Donaldson 1982; Arndt and Nisbet 1982), and the distribution
and variation in size of olivine grains in spinifex textures are commonly
used to delineate flow units and to determine facing directions in sequences
of flows (Pyke et al. 1973; Barnes et al. 1974; Pyke 1982).

The Pyke Hill outcrop is unique and has already suffered damage from
visitors. Please do not use hammers or dislodge samples here. This outcrop
lies 300 meast of the abandoned Potter Mine, at the edge of the
tailings pond. The outcrop is comprised of unusually well exposed and little
altered komatiitic lava flows described by Pyke et al. (1973) and Arndt
and Naldrett (1987). The spectacular spinifex bearing flows are an end
member of a continuum from spinifex rich flows to uniform ones in which
spinifex is absent. A map of the outcrop is shown
in figure Nl3. Typical sections through the end member flows are shown
in figure Nl4. The following description is taken from Arndt and Naldrett
(1989).

The spinifex-textured flows consist of:

Al zone - sparse olivine phenocrysts in a matrix of altered glass. This
is the flow top and displays joints (cooling cracks) breaking it up into
polyhedra;

A3 zone - olivine blades develop as randomly oriented books that begin
to align at right angles to the flow;

B1 zone - thin zone of tabular skeletal olivine grains;

B2 zone - polyhedral and equant olivine occupies up to 80 percent of
the rock with interstitial augite needles and altered glass;

B3 zone - knobby weathering of clots of augite rich matrix is distinctive
here, but not common In komatiites outside Munro township;

B4 zone - olivine gives way to altered glass in this basal chill zone
of the flow.

More than half of the olivine porphyritic flows on Pyke Hill have no spinifex
texture. They are pervaded by polygonal jointing, which is more intense
near the flow margins. In the southwest portion of the outcrop lava toes
are well exposed. They have massive interiors but their margins are defined
by zones of intense polygonal jointing.
6.3.1. Komatiite Lava Lake
Arndt (1986) has described a komatiite lava lake in the centre of Munro
Township (Fig. Nl5 and Nl6) and the following Is a summary of his findings.
The lava flows face to the north, and the oldest rocks, in the southwest,
are normal spinifex-textured and massive komatiites. The lava lake immediately
overlies these flows, and is in turn overlain by a thick sequence of mainly
mafic pyroclastic rocks. A small deposit in the upper part of the sequence,
the Potter Mine, is found in the upper part of the pyroclastic sequence
of komatiite flows. These are on strike with the Pyke Hill komatiite flows
some 300 metres to the east. On the east side of the lava lake, the volcanic
rocks are intruded by, or are in faulted contact with, gabbros from the
upper portion of a large layered mafic-ultramafic intrusion called the
Centre Hill complex (MacRae 1969). This contact will be described below.

The flows at the top of the sequence are normal spinifex-textured and
massive komatiites. They range in thickness from one to thirteen metres
and have textures and mineralogies just like those of Pyke Hill, described
above. The flow sequence underlying the lava lake is made up of komatiites
and pyroxene spinifex-textured basalts.

The lava lake is about 120 metres thick (Fig. Nl5). The lower two-thirds
is composed of massive, medium-grained dunite, now largely but not completely
serpentinized, and upper third is composed of fine-grained olivine porphyry.
The upper 30 to 40 metres of the unit are cut by veins with unusual swirling
tabular olivines, and in the uppermost 10 to 20 metres numerous spinifex-textured
veins appear.

6.3.1.1. Dunite
The dunite is an olivine accumulate. Before serpentinization most samples
contained between 70 and 80 percent olivine and minor chromite. Where the
olivine grains are not intergrown and do not interfere with one another,
most of them are euhedral or distinctly rounded, but a small fraction are
more elongate and tabular. Grain size varies from about one millimetre
in the lower 20 metres to a maximum of about two millimetres halfway up
through the unit. The olivines have relatively uniform compositions, with
cores of Fo89 and margins of Fo88. Other cumulus
phases are chromite, which occurs as relatively large (0.2 millimetre)
euhedral grains, and altered orthopyroxene.
6.3.2. Centre Hill Complex
The Munro Lake sill, according to MacRae (1969), is a grossly layered intrusion
exposed in three principal areas: Centre Hill, McCool Hill, and a broad
area at the boundary between Warden and Munro townships. The body is indicated
to be continuous by aeromagnetic maps, and the stratigraphic sequences
or rock layers in the three principal sections are strikingly similar.
The sill is approximately 11 kilometres in length and 500 to 1000 metres
thick. It is folded along a major east-west syncline having almost vertical
limbs, and is complexly broken by both longitudinal and cross faults. Minor
folds are common on both limbs, especially between Centre Hill and the
Warden-Munro areas.

The Centre Hill outcrop area is the only one showing a complete stratigraphic
section of the Munro Lake sill between its lower and upper contacts. Within
the exposure at Centre Hill, the intrusion is essentially vertical. It
generally has an east strike, but it is folded sharply southward at its
western end where MacRae (1969) interpreted it to be dragged against and
cut off by the Centre fault (Fig. Nl2). Both the
northern and southern (or upper and lower) contacts of the sill with volcanic
rock are exposed. On the north it has intruded a mafic fragmental rock
and on the south, basalt. The contacts are sharp and at places there is
a slight intertonguing of the intrusive and volcanic rocks. Immediately
adjacent to the lower contact, the intrusive rock may have been slightly
chilled, but an exact interpretation is difficult because of the subsequent
metamorphism and alteration of the rock.

The following description of the Complex is provided by Coad (1976).
"The complex is not a simple layered body, but is composed of many alternating
layers of ultramafic and mafic rocks. MacRae (1969) recognizes seven cyclic
units. The lower five consist of successive layers of peridotite and clinopyroxenite,
the sixth is composed of clinopyroxenite and gabbro and the upper most
seventh unit consists of a layer of melanocratic gabbro overlain by normal
gabbro. The ultramafic layers range in thickness from one to fifty metres
and lie in sharp contact with each other. The uppermost gabbroic unit is
over 200 metres thick. At the lower contact there is a unit of hornblendite
ten to thirty metres thick."

The uppermost gabbro unit is overlain by a fragmental rock which is
best described as a pillow breccia. This particular rock unit was previously
mapped as a rhyolite agglomerate (Satterly 1951); however, It has a composition
intermediate between a tholeiitic olivine basalt and picritic basalt. The
contact between the pillow breccia and gabbro appears to be faulted where
examined in aerial photographs and is seen to be sheared where exposed.
The pillow breccia outcrops over a stratigraphic thickness of approximately
60 metres. Drill hole information, together with extrapolation of rook
unit thicknesses along strike, indicate that this thick unit of fragmental
rock is approximately 75 metres thick in the east, but becomes progressively
thinner towards the west, along strike. The eastern extension of the pillow
breccia is not exposed because of extensive drift cover and major north
south faulting along the eastern edge of the Centre Hill complex. Pillow
breccia is stratigraphically overlain by komatiitic lava. To the west,
outcrop exposure of the pillow breccia is not continuous along the top
of the Centre Hill complex, but drill hole data, together with outcrop
exposure further to the west, indicates that this rock unit grades laterally
along strike into hyaloclastite (Coad 1976).

6.3.3. Potter Mine
The Potter mine is located in the central portion of Munro township immediately
north and west of the Centre Hill complex (Fig. Nl1). Arndt (1975) suggests
that this complex, a large differentiated peridotite/gabbro body, lies
on the southern limb of the major west plunging synclinal structure referred
to previously, and that it may be correlated with Theo's flow on the northern
limb of the same structure. The Centre Hill complex compares in some respects
with Theo's flow. However, the hyaloclastite which forms, a cap to the
Centre Hill body grades westward along strike into pillow breccia. Hyaloclastite
is not restricted to the top of the complex but intertongues with komatiitic
lavas forming three discrete horizons further to the west. The aphanitic
pyroxenite member of Theo's flow is absent from the Centre Hill complex;
instead a massive, ropy, brecciated, quench-textured tholeiite commonly
occurs between the hyaloclastites and the gabbro forming the top of the
underlying complex. A further difference is that the complex consists of
a number of cyclic mafic and ultramafic units in contrast to the continuous
progression of Theo's flow (Coad 1976).

It seems a curious coincidence that the mine overlies the junction of
the Centre Hill complex to the east and the Komatiite lava lake to the
west. The zone of shearing between these was always assumed to be a fault
by MacRae (1969) and others. However the excellent mapping, drill core
logging and petrography described by Coad (1976), which is referenced extensively
in this section, permits another interpretation. He shows that the hyaloclastite
and the mineralized horizons of the Potter Mine lie at the same levels
without offset either side of the shear zone. Although some faulting undoubtedly
did occur, part of it may have been synvolcanic,and the zone
is an excellent candidate for a feeder zone for the mineralization. It
is quite possible that the lava lake and the Centre Hill sill or flow lie
close to their original positions and represent a facies change.

6.3.3.1. Mine History and Geology
The copper at the Potter Mine was first investigated in the 1920's. In
1952 the Centre Hill Mines Ltd. commenced exploration that included 12,190
metres of drilling in 1956. In 1957 a shaft was sunk to 125 metres. The
deposit came under the control of Zenmac Metal Mines Limited in 1959 and
in 1964 underground exploration resumed. In 1967 production commenced from
a shaft deepened to 295 metres, using an on site mill rated at 710 tonnes
per day. The mine was sold to the Patrick Harrison Company Limited in 1969
and closed in 1972. Between 1967 and 1972, 485,210 tonnes of ore were milled
at an average grade of 1.63 percent Cu, 1.5 percent Zn, 3.1 to 15.5 g Ag/tonne
and traces of gold.

The following descriptions are directly taken from Coad (1976). "The
mine geology is characterized by two distinct volcanic series, namely komatiitic
lavas and tholeiitic olivine basalts. The komatiitic lavas consist predominantly
of picritic flows and intercalated with these flows are massive peridotitic
komatiites, characterized by an MgO content greater than 30 percent. The
massive peridotitic komatiites are not characterized by associated flow
tops marked by spinifex texture. The tholeiitic and olivine basalts are
chemically distinct from the komatiitic lavas and consist of three different
rock types: 1) hyaloclastite; 2) quench-textured tholeiite; and 3) pillow
breccia. Although volumetrically insignificant, thin beds of volcanic ash
occur at the top of the hyaloclastite horizon and actually represent a
third distinct rock sequence, having a dacitic composition."

The predominant rock type in the central portion of the map area is
hyaloclastite, a term used to describe a fragmental consisting of pea-sized
fragments of pillow breccia and glass (Coad 1976). The hyaloclastite is
commonly stratigraphically underlain by quench-textured tholeiitic lava
which outcrops over a stratigraphic thickness of approximately 12 metres.
The hyaloclastite matrix can consist of ash and fine grained carbonate,
quartz, plagioclase and up to 19 percent disseminated graphite (Coad 1976).
Volcanic ash occurs at the top of the hyaloclastite units. This ash is
composed of grains of quartz and broken plagioclase crystals and it locally
is banded and shows load-cast structures (Coad 1976). Thin layers (<0.5
metres) of chert also occur within the ash unit (Coad 1976). The hyaloclastite
and quench-textured tholeiite form a wedge-shaped mass at the western end
of the Center Hill complex which have been drag-folded and down-faulted
stratigraphically into place, or, may have formed approximately in their
current position (Coad 1976).

Coad (1976) provides the following description of the pyroclastic rocks
in this area. "The pyroclastic sequence contains a lower portion of crudely-bedded
well-sorted basaltic scoria and an upper portion of coarser agglomerates
and welded spatter, also with basaltic composition and also crudely bedded
or massive. Fragments in the scoria average 0.5 to 1 millimetres across.
Most are approximately equidimensional, with shapes varying from subangular
to rounded, to amoeboid or ribbon-like. Some smaller grains in the matrix
have shard shapes. Textures vary considerably, from originally completely
glassy (now altered to chlorite), to fine-grained porphyritic with small,
altered olivine and clinopyroxene phenocrysts, and in rare cases microspinifex.
Most fragments are not amygdaloidal or contain only sparse amygdules (1
to 2 percent), but some fragments have 10 to 15 percent. Amygdules are
less than 0.5 millimetres across. One or two fragments in each thin section
have a wispy, patchy, ribbon-like form and may be squashed pumice. Each
thin section also contains a few, usually larger, angular fragments of
exotic rock types such as feldspar-porphyritic felsic volcanics, pale cream
relatively pure cherts, and dark-coloured graphite- rich (?) cherts. The
matrix is cryptocrystalline cherty quartz, feldspar and chlorite, or carbonate."

"The agglomerates higher in the unit have fragment sizes between one
and fifty centimetres, usually around two to five centimetres. Fragments
are rounded or have complex amoeboid shapes. They are commonly deformed
and moulded against adjacent fragments. They also have basaltic composition
and fine grained aphanitic or olivine clinopyroxene porphyritic texture."

6.3.3.2. Mineralization

Massive and matrix sulphide mineralization at the Potter Mine consists
predominantly of pyrrhotite, equal proportions of sphalerite and chalcopyrite,
and minor pyrite (Coad 1976). Economic concentrations of sulphide mineralization
are restricted to the hyaloclastite horizon, but sulphides were remobilized
along shears into the adjacent picritic basalt flows (Coad 1976). Iron-rich
sphalerite occurs throughout the hyaloclastite horizon, associated with
chalcopyrite and pyrrhotite. Iron-poor sphalerite occurs at the top of
the hyaloclastite horizon (Coad 1976).

Matrix sulphide is the more common habit, whereby sulphides occupy the
interstices between fragments of glass, pillow breccia of the hyaloclastite
(Coad 1976). The matrix or disseminated sulphide grades into massive sulphide
lenses. Massive ore lenses occur within the upper hyaloclastite horizon,
althoughsome massive ore may also have occurred in the lower hyaloclastite
(Coad 1976). These lenses, ranging from 15 to 30 metres in length, lie
directly on top of the hyaloclastite horizon. The massive sulphide lenses
average one metre in thickness, but are continuous in the vertical dimension
to a depth of 365 metres (Coad 1976). The massive sulphide lenses were
commonly banded with respect to chalcopyrite, sphalerite, and pyrrhotite
(Coad 1976).

The massive sulphide is intimately related to volcanic ash which occurs
throughout the hyaloclastite unit, but which is more abundant at the top
of the unit (Coad 1976). The upper surface of the massive sulphide lense
lies in sharp contact with the chilled base of the overlying picritic (komatiitic)
flows (Coad 1976). A thin concentration of iron-poor sphalerite may occur
along this upper contact (Coad 1976).

Coad (1976) did not observe stringer mineralization. However, stringer
mineralization, associated with chlorite alteration, was reported to occur
in an area of the mine that was disrupted by shearing (Coad 1976, p.144).
Chlorite also occurs as a matrix mineral where the hyaloclastite is sheared
or mineralized with sulphides (Coad 1976).

6.3.3.3. Metal Zoning

Despite the abundance of komatiites in this area, the sulphide mineralization
did not contain significant nickel, and averaged only 0.03 weight percent
(Coad 1976, p. 172). The copper/zinc ratiowas close to or less
than one (Coad 1976), although the massive ore was zoned from a zinc-rich
top to a copper-rich base (Coad 1976). Zinc grades were much less in the
vicinity of the strong chlorite alteration zone, supporting the premise
that the chlorite alteration represented a feeder-pipe (Coad 1976). Nickel/cobalt
ratios of the ore wereless than one (Coad 1976).

6.3.3.4. Genesis

According to Coad (1976), the source of metals concentrated in that
mine is probably the mafic-ultramafic magma represented by the Centre Hill
Complex, in particular the gabbro member. The metals were probably transported
either by primary hydrothermal fluids escaping during magmatic differentiation
or by secondary leaching involving the convection of sea water. Whether
or not sea water penetrated the gabbro, a combination of solutions was
probably instrumental in the transportation of metals from the gabbro member
of the Centre Hill complex through the overlying hyaloclastite units. The
sulphur may have been derived from both sea water and the magma (Coad 1976).